The present invention is directed to treatment of liquid compositions that are useful as biomedical adhesives and sealants, particularly methods of sterilizing them. More particularly, the present invention relates to a method using electron beam irradiation to sterilize monomeric liquid adhesive compositions, for example 1,1-disubstituted ethylene monomers. 2. Description of Related Art
Several methods are known for sterilizing monomeric and polymeric compositions.
U.S. Pat. No. 5,530,037 to McDonnell et al. discloses sterilizing cyanoacrylates using gamma radiation. Additionally, several other methods are disclosed including ionizing radiation. However, most of these methods are said to be unsuitable in their applicability to cyanoacrylate adhesives. In particular, the '037 patent states that electron beam accelerators have relatively low penetration and are effective only in sterilizing the outer surface of a container.
U.S. Pat. No. 2,904,392 to Pomerantz et al. discloses a method of packaging various chemicals, gasoline, polymerized plastics, or polymerizable monomers in film-formed bags and subjecting the bags to high intensity ionizing irradiation to effect sterilization. The radiation is obtainable from beams of high energy electrons produced by high voltage electron accelerators. In the case of monomers, irradiation at a suitable dosage level can be utilized to initiate polymerization without the assistance of a chemical catalyst or promoter. In this manner, polymerization can be achieved at low temperatures and the resultant polymer is essentially pure.
U.S. Pat. No. 3,704,089 to Stehlik discloses a process for the sterilization of monomeric esters of .alpha.-cyanoacrylic acids. The sterilization is carried out by ionizing irradiation (e.g., Co 60-gamma irradiation) after the esters have cooled, preferably to below their solidification points.
U.S. Pat. No. 2,921,006 to Schmitz et al. discloses polymerization of organic compounds with high energy electrons and, more particularly, polymerization of such compounds in the liquid or solid state by irradiation with high energy electrons. The organic compounds are contained in a receptacle covered with an aluminum sheet.
U.S. Pat. No. 3,122,633 to Steigerwald discloses an apparatus for polymerization of liquid materials by subdividing a polymer organic material into small volumes and irradiating the material while in the subdivided state with an electron beam source.
U.S. Pat. No. 3,780,308 to Nablo discloses surface sterilization and/or surface treatment of containers and other articles, the walls of which have a high specific energy absorption for relatively low energy electrons. The electron beam slightly penetrates container walls to effect surface sterilization, while substantially absorbing the electrons within the walls to minimize x-ray generation.